Geoffrey of Monmouth’s Historia regum Britanniae (c. 1136) changed the course of history writing for centuries. It newly provided the Britons with a substantial role in the insular past and inspired the writing and copying of several Brut chronicles. This chapter surveys the development of Brut chronicles in England, in terms of the incorporation of legendary British history into accounts of Anglo-Saxon and later English rulers. It then focuses on one Brut history, the Prose Brut – the most popular secular, vernacular text written in late medieval England – looking at this chronicle’s reshaping of Geoffrey’s Historia at the transfer from British to English power. An exploration of the role of Cadwallader in the Prose Brut provides a case study to consider some of the ways in which the chronicle reshaped this period in the past in its original Anglo-Norman version (the Oldest Version) and then in later versions, written in English. The Oldest Version reimagined the British, Anglo-Saxon, and Norman conquests, providing a distinctive account of Brutus’s foundation of Britain and describing William’s reign in positive terms. But most strikingly, the Oldest Version omitted Cadwallader – Geoffrey of Monmouth’s last British king – from its narrative of the past. However, many English Prose Bruts added the famous ruler back into the historical record. Their distinctive account of Cadwallader’s reign shows some of the ways in which medieval writers reflected on moments of conquest and on the transitions between peoples in this history. Brut texts and manuscripts are ripe for further critical study.